Using a metric ruler student A measured the length of an object to
the nearest tenth (0.1) of a centimeter, while student D measured its
length to the nearest centimeter. Which measurement is more accurate?

A student seeks clarity with the significant digits required after converting a
measurement from US customary units to metric. Reinforcing how precision applies to
measured data, Doctor Peterson walks through an example.

How do you convert units to a different measurement? And how do you know how
many decimal places to move as a result? Doctor Ian suggests making the
multiplication of units explicit, and introduces ratios of two quantities equal to each
other.

Given five 4 ft by 8 ft rectangular sheets of plywood, how many strips
that are 7 1/2 inches wide and 8 feet long could you cut? Each saw cut
eliminates 1/16 inch of the plywood as sawdust, and you are not able
to glue any strips together.

I'm confused about how to decide if a number is exact or inexact. I know
that in general measurements are considered inexact, but how about
conversion factors such as 1 inch = 2.54 cm? The exactness of the
number plays a role in the number of significant digits to keep. What
other kinds of numbers are considered exact and inexact?

I'm an 8th grade student working on greatest possible error and it
just doesn't seem to make any sense. I know that GPE is half of the
smallest unit of measure, but I don't understand how to decide what
the smallest unit of measure is.

Why are English measures inconsistent in conversions? The metric
system works in the meter and power of tens, but English units are
kind of crazy (1 ft = 12 in, 3 ft = 1 yd, 1 mi = 1760 yd or 5280 ft,
etc.).